Prior to the mid-nineteenth century, each Mijikenda group lived together in or near its own kaya. Each kaya was located in a cleared, circular glade on a hilltop, surrounded by dense forest. At the center of the kaya were the meeting houses of the different clans. Surrounding each clan house were the individual residences of its members. The clans were unilinealdescent groups that were primarily patrilineal, and this pattern varied from kaya to kaya. The number of clans remained constant, but each clan was further divided into subclans, which increased in number as new members were born into the group and as alien groups were adopted. Each subclan was further divided into local lineage groups that lived together in homesteads. The homestead averaged three generations, but its membership was not fixed. The ideal homestead included a man, his sons, and his grandsons, but sons could form their own separate homesteads.
The clans played a central role in kaya affairs. Each clan had its own area within the kaya and its own specialized function. The subclans were not important political units, but they played an important role in the social life of the Mijikenda, particularly with regard to the organization of major social evevts, such as weddings and funerals. The local lineage was the local residential group that farmed the land corporately held by the homestead head.
Each kaya was divided by age as well as by descent. The men of the kaya were formed into age sets (sing. rika ), and the members of a given age set progressed together from childhood through adolescence to adulthood. The age sets existed on two levels. Every four years, the uninitiated boys were circumcised and initiated into a sub-rika. When thirteen such sub-rikas had been initiated, all were then corporately initiated as the next rika. The senior three sub-rikas ruled for twelve years and were succeeded by the following two sub-rikas, which ruled for eight years. This pattern continued by pairs until all thirteen sub-rikas had ruled as senior elders, at which time the succeeding thirteen sub-rikas were initiated as the next rika.